Sillimanite

	Email		Print
	Bookmark		Link

Sillimanite

Sillimanite also called Bucholzite is an alumino-silicate mineralMineral

Minerals are natural compounds formed through geological processes....
with the chemical formulaChemical formula

A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compoun...
Al₂SiO₅. Sillimanite is named after the American chemist Benjamin SillimanBenjamin Silliman

Benjamin Silliman was one of the first American professors of science....
.

Occurrence

Sillimanite is one of three alumino-silicate polymorphsPolymorphism (materials science) Overview

Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure....
, the other two being andalusiteAndalusite Overview

Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5....
and kyaniteKyanite

Kyanite, whose name derives from the Greek word kyanos, meaning blue, is a typically blue silicate mineral, commonly fou...
. A common variety of sillimanite is known as fibrolite, so named because the mineral appears like a bunch of fibres twisted together when viewed under thin section or even by the naked eye. Both the fibrous and traditional forms of sillimanite are common in metamorphosedMetamorphism

Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressur...
sedimentary rockSedimentary rock

Sedimentary rock is one of the three main rock groups and is formed in three main ways—by the deposition of the weath...
s. It is an index mineralIndex mineral

An index mineral is used in geology to determine the degree of metamorphism a rock has experienced....
indicating high-temperature metamorphism.

Sillimanite has been found in Brandywine Springs, New Castle County, DelawareDelaware Overview

Delaware is one of five Middle Atlantic States in the United States of America.ography...
, USA. By suggestion of the members of the , it was named by the State Legislature in 1977 as the .

Details

Crystallographic systemCrystal structure In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal....	Orthorhombic
Colours	White, brown and green
Lustre	Silky if in fibrous form, else vitreous
HardnessMohs scale of mineral hardness Mohs' scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder mat...	7.5
Refractive indexRefractive index The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed in that...	1.641-1.648
Cleavage	1
Twinning	n/a
PleochroismPleochroism Overview Pleochroism is an optical phenomenon where due to double refraction of light by a colored gem or crystal, the light is divid...	Colourless to pale brown to yellow
Type locality	VltavaFacts About Vltava The Vltava listen is the longest river in the Czech Republic, draining into the north from its source in umava through Cesk... , Susice, Czech RepublicCzech Republic The Czech Republic , a member state of the European Union , is a landlocked country in Central Europe.... .

Sillimanite

Occurrence

Details

See also

External links